FOSSIL AND RECENT 127 



adjacent to an open groove upon the supratemporal, contains the lateral portion of 

 the supratemporal commissure. In lateral view (Text-fig. 61) the endochondral 

 portion of the pterotic is seen to form the greater part of the dilatator fossa, the pos- 

 terior half of the hyomandibular facet and the roof of the deep subtemporal fossa. 

 Beneath the hyomandibular facet the pterotic is marked by an arc-shaped swelling 

 which marks the path of the horizontal semicircular canal. The medial surface of 

 the pterotic forms the roof, the lateral wall and part of the floor of the post-temporal 

 fossa. 



In dorsal view the supraoccipital (Text-fig. 60) is seen to separate the parietals 

 posteriorly. Two antero-laterally directed wings of the supraoccipital extend beneath 

 the parietals and contact the autosphenotic. The anterior wings also form the 

 inner wall of the post-temporal fossae. In posterior view (Text-fig. 63) the supra- 

 occipital is small, semicircular and separated from the exoccipital by a large area of 

 cartilage. The supraoccipital crest is very small. 



Between the supraoccipital and pterotic lies the irregularly shaped epiotic (Text- 

 figs. 60, 63). A narrow band of cartilage separates the epiotic from the exoccipital. 

 The posterior vertical semicircular canal runs through the epiotic and its path may be 

 seen externally as a ridge running along the medial margin of the post-temporal 

 fossa and forming an arc above the subepiotic fossa. The epiotic process is weakly 

 developed. 



The exoccipital (Text-fig. 61) forms the posterior wall of the subtemporal fossa 

 and part of the large otic bulla. Three foramina are present on the lateral face of the 

 exoccipital : anteriorly there is a glossopharyngeal foramen which is preceded by a 

 shallow groove, then follows a small foramen for a blood vessel, and posteriorly a 

 large, ventrally directed vagus foramen. The posterior face of the exoccipital 

 (Text-fig. 63) forms the ventral half of the subepiotic fossa. The exoccipital meets 

 its fellow above and below the foramen magnum. The lateral and posterior faces 

 of the exoccipital meet in a pronounced thickening, within which run the horizontal 

 and posterior vertical semicircular canals. 



At the lower margin of the opening to the post-temporal fossa there is an area of 

 cartilage between the exoccipital, pterotic and epiotic. Covering this cartilage is the 

 intercalar which, as in all albuloids, is relatively small. The posterior surface of the 

 intercalar is ridged, providing a surface of attachment for a tendon from the intercalar 

 limb of the post-temporal. Laterally the intercalar curves antero-ventrally and in 

 one specimen examined (Text-fig. 61) forms the dorsal margin of the vagus foramen. 



The basioccipital forms the occipital condyle, the posterior portion of the myodome 

 roof and the walls of the saccular recess of either side. The vertebral-like expansion 

 of the basioccipital shows a deep notochordal pit, which is not quite symmetrical 

 since the ventral margin lies more horizontally than the dorsal. Between the bullate 

 portion and the occipital expansion the lateral surface of the basioccipital is rough, 

 providing an anchorage point for a strong ligament passing to the cleithrum/supra- 

 cleithrum overlap. Ventrally the basioccipital is marked by a shallow groove which 

 is continuous with a small groove upon the parasphenoid. 



The prootic is, as usual, a bone of complex shape. The lateral face contributes 

 to the formation of the hyomandibular facet, the subtemporal fossa and the otic 



